In many industrial applications, such as the manufacture of foods and beverages, hard surfaces commonly become contaminated with soils such as carbohydrate, proteinaceous, and hardness soils, food oil soils and other soils. Such soils can arise from the manufacture of both liquid and solid foodstuffs. Food and beverage soils are particularly tenacious when they are heated during processing. Foods and beverages are heated for a variety of reasons during processing. For example, many food and beverage products are concentrated or created as a result of evaporation.
Specific examples of food and beverage products that are concentrated using evaporators include dairy products such as whole and skimmed milk, condensed milk, whey and whey derivatives, buttermilk, proteins, lactose solutions, and lactic acid; protein solutions such as soya whey, nutrient yeast and fodder yeast, and whole egg; fruit juices such as orange and other citrus juices, apple juice and other pomaceous juices, red berry juice, coconut milk, and tropical fruit juices; vegetable juices such as tomato juice, beetroot juice, carrot juice, and grass juice; starch products such as glucose, dextrose, fructose, isomerose, maltose, starch syrup, and dextrine; sugars such as liquid sugar, white refined sugar, sweetwater, and insulin; extracts such as coffee and tea extracts, hop extract, malt extract, yeast extract, pectin, and meat and bone extracts; hydrolyzates such as whey hydrolyzate, soup seasonings, milk hydrolyzate, and protein hydrolyzate; beer such as de-alcoholized beer and wort; and baby food, egg whites, bean oils, and fermented liquors.
There are generally at least two sides to an evaporator. One side holds the steam or vapor heat source (typically at temperatures of about 212° F. to 350° F.). The other side holds the process liquid to be concentrated. During the evaporation process, the liquid to be concentrated is introduced into the evaporator. The heat exchange across the tubes or plates evaporates water off the process stream concentrating the liquid solids. The liquid to be concentrated may be run through an evaporator several times (or a series of several evaporators) until it is sufficiently concentrated.
There are many different types of evaporators including falling film evaporators, forced circulation evaporated evaporators, plate evaporators, circulation evaporators, fluidized bed evaporators, falling film short path evaporators, rising film evaporators, counterflow-trickle evaporators, stirrer evaporators, and spiral tube evaporators. In addition to the evaporators, there are several other pieces of equipment in an evaporation plant including preheaters and heaters, separators, condensers, deaeration/vacuum systems, pumps, cleaning systems, vapor scrubbers, vapor recompression systems, and condensate polishing systems. All of the evaporation plant equipment should be cleaned, however, the actual evaporator typically has the most difficult soiling problems.
When a food or beverage product contacts any surface, soiling occurs where some part of the food or beverage product is left behind on that surface. When that surface is a heat exchange surface, the soil becomes thermally degraded rendering it even more difficult to remove. Over time, the layer of soil increases in thickness as more food or beverage product is passed over the heat exchange surface. The layer of soil acts as an insulator between the heat and the product being heated, thereby reducing the efficiency of the heat exchange surface and requiring more energy to create the same effect if the heat exchange surface were clean. When the heat exchange surface is an evaporator, the difference between a clean heat exchange surface and a soiled heat exchange surface can mean the difference in millions of dollars in energy costs for an evaporator plant. With the cost of energy increasing significantly, as well as an increased awareness of protecting the environment by preserving natural resources, there remains a need for cleaning programs that can clean heat exchange surfaces and create an efficient transfer a heat.
Cleaning techniques for removing scale and other fouling/soils from the internal components of the evaporators, including vessels or tanks, lines, and the like require passing cleaning solutions through the system (often without dismantling any system components such as commonly used in CIP techniques). The techniques involves allowing the cleaning solution to pass through the equipment and maintain contact with the scale or soil (such as in the vessels or tanks of the evaporators) before resuming normal processing. The process can also include any additional contacting and/or rinsing steps in which a rinse, acidic or basic functional fluid, solvent or other cleaning component such as hot water, cold water, etc. can be contacted with the equipment at any step during the process. The cleaning techniques require a complete shutdown of the equipment being cleaned, which results in lost production time. Many times, the equipment is not thoroughly cleaned. In many conventional cleaning processes for sugar evaporators, EDTA or other calcium chelants such as citric acid are applied at concentrations of at least about 5% to remove scale. The chelants can be provided in alkaline, neutral, or acidic solutions. Often, highly alkaline concentrations of EDTA at pH of at least about 11-12 are conventionally employed. However, such concentrations are often insufficient for removal of the scale and increased concentrations, such as 10% or greater, are applied at elevated pH, elevated temperature and/or using mechanical force to attempt to increase scale removal efficiency within sugar evaporators. There is still however a need for improved methods and compositions for cleaning this equipment.
It is against this background that the present invention has been made. In general, the prior art provides insufficient cleaning compositions and/or automated methods for the cleaning of evaporators, such as sugar evaporator. Therefore, improved cleaning compositions and processes are required to remove soils, deposits, and other impurities.
Accordingly, it is an objective of the claimed invention to develop sugar or sugar-moiety containing cleaning compositions for improved cleaning of evaporators.
According to the invention, it is desired to reduce the time and difficulty of cleaning evaporators by providing improved cleaning compositions.
A further object of the invention is to develop compositions and methods for use to completely remove scale from evaporators.
Other objects, advantages and features of the present invention will become apparent from the following specification taken in conjunction with the accompanying drawings.